In recent years, in reflection of the need for higher-speed communication and more compact communication devices, there has been an increasing demand for a lens array in which a plurality of lenses are arranged in parallel, as a compactly structured optical component effective for actualizing multichannel optical communication.
This type of lens array is conventionally configured such that a photovoltaic device including a plurality of light-emitting elements (such as a vertical cavity surface emitting laser [VCSEL]) can be attached thereto and a plurality of optical fibers can be attached thereto.
In a state in which the lens array is disposed between the photovoltaic device and plurality of the optical fibers in this way, the lens array optically couples light emitted from each light-emitting element of the photovoltaic device to an end face of each optical fiber. As a result, multichannel optical communication can be performed.
In addition, among photovoltaic devices, some include a monitoring light-receiving element for monitoring light (particularly intensity or amount of light) emitted from the light-emitting elements to stabilize the output characteristics of the light-emitting elements. A lens array supporting such photovoltaic devices is configured to reflect some of the light emitted from the light-emitting elements towards the monitoring light-receiving element as monitor light.
Furthermore, among the photovoltaic devices, some include a receiving light-receiving element in addition to the light-emitting elements to support bidirectional communication. A lens array supporting such photovoltaic devices include a lens for reception in addition to a lens for transmission.
An example of the lens array supporting light monitoring and an example of the lens array supporting bidirectional communication will hereinafter be described in sequence.
(Light Monitoring-supporting Lens Array)
First, FIG. 20 is a vertical cross-sectional view showing a lens array 1 supporting light monitoring, together with a photovoltaic device 2 and optical fibers 3. In addition, FIG. 21 is a planar view of a lens array main body in the lens array 1 shown in FIG. 20. FIG. 22 is a left-side view of the lens array main body shown in FIG. 20. FIG. 23 is a bottom view of the lens array main body shown in FIG. 20. FIG. 24 is a right-side view of the lens array main body shown in FIG. 20.
As shown in FIG. 20, the lens array 1 is disposed between the photovoltaic device 2 and the optical fibers 3.
Here, the photovoltaic device 2 has a plurality of light-emitting elements 7 on a surface of a semiconductor substrate 5 facing the lens array 1, the light-emitting elements 7 emitting laser light La in a direction perpendicular to the surface (upward direction in FIG. 20). The light-emitting elements 7 configure the above-described VCSEL. In FIG. 20, the light-emitting elements 7 are formed in an array along a direction perpendicular to the surface of the paper on which FIG. 20 is printed. In addition, the photovoltaic device 2 has a plurality of monitoring light-receiving elements 8 on the surface of the semiconductor substrate 5 facing the lens array 1, in positions near the left-hand side in FIG. 20 of the light-emitting elements 7. The light-receiving elements 8 receive monitor light M for monitoring the output (such as intensity or amount of light) of the laser light La emitted from the light-emitting elements 7. The number of light-receiving elements 8 is the same as the number of light-emitting elements 7. The light-receiving elements 8 are formed in an array in the same direction as the light-emitting elements 7. The positions in the array direction match between corresponding elements 7 and 8. In other words, the light-receiving elements 8 are formed at the same pitch as the light-emitting elements 7. The light-receiving elements 8 are configured by photodetectors or the like. Furthermore, a control circuit (not shown) that controls the output of the laser light La emitted from the light-emitting elements 7 based on the intensity and the amount of light of the monitor light M received by the light-receiving elements 8 is connected to the photovoltaic device 2. The photovoltaic device 2 such as this is configured, for example, to be arranged opposing the lens array 1 in a state in which the semiconductor substrate 5 is in contact with the lens array 1. The photovoltaic device 2 together with the lens array 1 configures an optical module by, for example, being attached to the lens array 1 by a known fixing means (not shown) such as a clamp spring.
In addition, the same number of optical fibers 3 as the number of light-emitting elements 7 and the number of light-receiving elements 8 are arranged. The optical fibers 3 are formed in an array at the same pitch as the light-emitting elements 7 along the direction perpendicular to the surface of the paper on which FIG. 20 is printed in FIG. 20. The optical fibers 3 have the same dimensions as one another. A portion of each optical fiber 3 on an end face 3a side is held within a multi-core integrated optical connector 10, such as a mechanically transferable splicing connector (MT connector). The optical fibers 3 such as this are, for example, attached to the lens array 1 by a known fixing means (not shown) (such as a clamp spring) in a state in which an end surface of the optical connector 10 on the lens array 1 side is in contact with the lens array 1.
The lens array 1 optically couples each light-emitting element 7 with the end face 3a of each optical fiber 3 in a state in which the lens array 1 is disposed between the photovoltaic device 2 and the optical fibers 3 such as those described above.
The lens array 1 will be described in further detail. As shown in FIG. 20, the lens array 1 has a light-transmissive lens array main body 4. The outer shape of the lens array main body 4 is formed into a substantially rectangular plate shape. In other words, as shown in FIG. 20 and FIG. 21, the rough outer shape of the lens array main body 4 is configured by each planar surface: an upper end surface 4a, a lower end surface 4b, a left end surface 4c, a right end surface 4d, a front end surface 4e, and a back end surface 4f. The upper and lower end surfaces 4a and 4b are parallel with each other. The left and right end surfaces 4c and 4d are also parallel with each other. Furthermore, the upper and lower end surfaces 4a and 4b and the left and right end surfaces 4c and 4d are perpendicular to each other.
The photovoltaic device 2 is attached to the lower end surface 4b of the lens array main body 4 such as this. As shown in FIG. 20 and FIG. 23, a plurality (12 lens faces) of first lens faces (convex lens faces) 11 having a circular planar shape are formed on the lower end surface 4b. The number of first lens faces 11 is the same as the number of light-emitting elements 7. Here, as shown in FIG. 20, a portion having a substantially rectangular planar shape in a predetermined area on the right side in FIG. 20 of the lower end surface 4b is formed into a recessing plane (referred to, hereinafter, as a lens formation surface 16a) that recesses further upwards than other portions with a counterbore 16 therebetween. The plurality of first lens faces 11 are formed on the lens formation surface 16a on the lower end surface 4b such as this. However, the lens formation surface 16a is formed in parallel with the other portions of the lower end surface 4b. In addition, the first lens faces 11 are formed such as to be arrayed in a predetermined array direction (the direction perpendicular to the surface of the paper on which FIG. 20 is printed in FIG. 20, and a vertical direction in FIG. 23) corresponding with the light-emitting elements 7. Furthermore, the first lens faces 11 are formed having the same dimensions as one another and are formed at the same pitch as the light-emitting elements 7. Still further, the first lens faces 11 that are adjacent to each other in the array direction are formed in an adjoining state in which respective peripheral end sections are in contact with each other. In addition, an optical axis OA(1) of each first lens face 11 is formed perpendicular to the lower end surface 4b of the lens array main body 4. Moreover, the optical axis OA(1) of each first lens face 11 is formed to match a center axis of the laser light La emitted from each light-emitting element 7 corresponding with each first lens face 11.
As shown in FIG. 20, the laser light La emitted from each light-emitting element 7 corresponding with each first lens face 11 enters each first lens face 11. Each first lens face 11 advances the incident laser light La of each light-emitting element 7 into the lens array main body 4. Each first lens face 11 collimates the incident laser light La of each light-emitting element 7 in some instances, and converges the incident laser light La in other instances.
On the other hand, the plurality of optical fibers 3 are attached to the left end surface 4c of the lens array main body 4. As shown in FIG. 20 and FIG. 22, a plurality of second lens faces (convex lens faces) 12 having a circular planar shape are formed on the left end surface 4c. The number of second lens faces 12 is the same as the number of the first lens faces 11. Here, as shown in FIG. 20 and FIG. 22, a portion having a substantially rectangular planar shape in a predetermined area in the center of the left end surface 4c is formed into a recessing plane (referred to, hereinafter, as a lens formation surface 17a) that recesses further to the right in FIG. 20 than other portions on the peripheral side surrounding the portion with a counterbore 17 therebetween. The plurality of second lens faces 12 are formed on the lens formation surface 17a on the left end surface 4c such as this. However, the lens formation surface 17a is formed in parallel with the other portions of the left end surface 4c. In addition, the second lens faces 12 are formed such as to be arrayed in the same direction as the array direction of the end faces 3a of the optical fibers 3, or in other words, the array direction of the first lens faces 11. Furthermore, the second lens faces 12 are formed having the same dimensions as one another and are formed at the same pitch as the first lens faces 11. Still further, the second lens faces 12 that are adjacent to each other in the array direction are formed in an adjoining state in which respective peripheral end sections are in contact with each other. In addition, an optical axis OA(2) of each second lens face 12 is formed perpendicular to the left end surface 4c of the lens array main body 4. Moreover, the optical axis OA(2) of each second lens face 12 is formed to be positioned coaxially with the center axis of the end face 3a of each optical fiber 3 corresponding with each second lens face 12.
The laser light La of each light-emitting element 7 that has entered each first lens face 11 corresponding with each second lens face 12 and advanced on an optical path within the lens array main body 4 enters each second lens face 12, as shown in FIG. 20. Each second lens face 12 converges the incident laser light La of each light-emitting element 7 and emits the converged laser light La to the end face 3a of each optical fiber 3a corresponding with each second lens face 12.
In this way, each light-emitting element 7 and the end face 3a of each optical fiber are optically coupled by the first lens face 11 and the second lens face 12.
Furthermore, as shown in FIG. 20 and FIG. 23, third lens faces (convex lens face) 13 having a circular planar shape are formed on the lens formation surface 16a on the lower end surface 4b of the lens array main body 4, in positions near the left-hand side in FIG. 20 of the first lens faces 11. The number of third lens faces 13 is the same as the number of the light-receiving elements 8 (according to the present embodiment, the number of third lens faces 13 is also the same as the number of light-emitting elements 7, the number of optical fibers 3, the number of first lens faces 11, and the number of second lens faces 12). The third lens faces 13 are formed such as to be arrayed in a predetermined array direction corresponding with the light-receiving elements 8, or in other words, the same direction as the array direction of the first lens faces 11. Furthermore, the third lens faces 13 are formed having the same dimensions as one another and are formed at the same pitch as the light-receiving elements 8. Still further, the third lens faces 13 that are adjacent to each other in the array direction are formed in an adjoining state in which respective peripheral end sections are in contact with each other. In addition, an optical axis OA(3) of each third lens face 13 is formed perpendicular to the lower end surface 4b of the lens array main body 4. Moreover, the optical axis OA(3) of each third lens face 13 is formed to almost match the center axis of a light-receiving surface of each light-receiving element 8 corresponding with each third lens face 13.
The monitor light M of each light-emitting element 7 corresponding with each third lens face 13 enters each third lens face 13 from within the lens array main body 4, as shown in FIG. 20. Each third lens face 13 converges the incident monitor light M of each light-emitting element 7 and emits the converged monitor light M towards each light-receiving element 8 corresponding with each third lens face 13.
Still further, as shown in FIG. 20 and FIG. 21, a first recessing section 18 having a substantially trapezoidal vertical cross-sectional shape is formed in a recessing manner on the upper end surface 4a of the lens array main body 4. A sloped surface 18a forming a portion of the inner surface of the first recessing section 18 serves as a total reflection surface 18a. As shown in FIG. 20, the total reflection surface 18a is formed into a sloped surface having a tilt in relation to both the lower end surface 4b and the left end surface 4c of the lens array main body 4 such that the upper end portion thereof is positioned further to the left side in FIG. 20 (in other words, towards a second recessing section 19, described hereafter) than the lower end portion thereof. In addition, as shown in FIG. 21, the planar shape of the total reflection surface 18a is formed into a substantially rectangular shape that is elongated in the array direction of the first lens faces 11 (a vertical direction in FIG. 21). The total reflection surface 18a is disposed on the optical path of the laser light La of each light-emitting element 7 between the first lens faces 11 and a first optical surface 19a of the second recessing section 19, described hereafter.
As shown in FIG. 20, the laser light La of each light-emitting element 7 that has entered each first lens face 11 enters the total reflection surface 18a such as this at an angle of incidence that is the critical angle or greater, from below in FIG. 20. The total reflection surface 18a totally reflects the incident laser light La of each light-emitting element 7 towards the left side in FIG. 20.
The tilt angle of the total reflection surface 18a is 40° to 50° (such as 45°) in the clockwise direction in FIG. 20, with reference to the lower end surface 4b (0°).
In addition, as shown in FIG. 20 and FIG. 21, the second recessing section 19 is formed in a recessing manner on the upper end surface 4a of the lens array main body 4 such as to be positioned on the optical path of the laser light La passing through the first lens faces 11 and the second lens faces 12. As shown in FIG. 20 and FIG. 21, the second recessing section 19 is formed such that the vertical cross-sectional shape is rectangular, and the planar shape is a rectangular shape that is elongated in the array direction of the first lens faces 11.
Here, as shown in FIG. 20, the first optical surface 19a forming a portion of the inner surface of the second recessing section 19 is formed on the right side surface of the second recessing section 19. The first optical surface 19a is formed in parallel with the left end surface 4c of the lens array main body 4.
As shown in FIG. 20, the laser light La of each light-emitting element 7 that has been totally reflected by the total reflection surface 18a perpendicularly enters the first optical surface 19a such as this. The angle of incidence (in other words, a direction of incidence) is an angle (direction of incidence) that is also perpendicular to the left end surface 4c. 
In addition, as shown in FIG. 20, a second optical surface 19b is formed on the left side surface of the second recessing section 19 such as to form a portion of the inner surface of the second recessing section 19 and form a portion opposing the first optical surface 19a on the left side in FIG. 20. The second optical surface 19b is also formed in parallel with the left end surface 4c. 
As shown in FIG. 20, the laser light La of each light-emitting element 7 that has entered the first optical surface 19a and subsequently advanced toward the second lens face 12 side perpendicularly enters the second optical surface 19b such as this. The second optical surface 19b then perpendicularly transmits the incident laser light La of each light-emitting element 7.
Furthermore, as shown in FIG. 20, a prism 20 having a trapezoidal vertical cross-sectional shape is disposed in a space formed by the second recessing section 19.
Here, as shown in FIG. 20, the prism 20 has a first prism face 20a forming a portion of the surface of the prism 20 in a position facing the first optical surface 19a on the left side in FIG. 20. The first prism face 20a is formed into a sloped surface having a predetermined tilt angle in relation to the lower end surface 4b and the left end surface 4c of the lens array main body 4 such that the upper end portion thereof is positioned further to the right side in FIG. 20 (in other words, towards the first optical surface 19a side) than the lower end portion thereof. As a result, as shown in FIG. 20, a space having a right-triangular vertical cross-sectional shape is formed between the first prism face 20a and the first optical surface 19a. 
In addition, as shown in FIG. 20, the prism 20 has a second prism face 20b that forms a portion of the surface of the prism 20 and forms a portion opposing the first prism face 20a. The second prism face 20b is disposed in parallel with the second optical surface 19b in a position facing the second optical surface 19b on the right side in FIG. 20 with a predetermined amount of space therebetween.
Furthermore, as shown in FIG. 20, the prism 20 is positioned in relation to the second recessing section 19 such that a right end surface in FIG. 20 is in contact with a portion extending upwards from the upper end of the first optical surface 19a on the right side surface of the second recessing section 19, a lower end surface in FIG. 20 is in contact with a bottom surface 19e (see FIG. 21) of the second recessing section 19, and a shoulder section 21 formed in the upper end portion is in contact with the upper end surface 4a of the lens array main body 4.
The prism 20 such as this forms the optical path of the laser light La of each light-emitting element 7 that has entered the first optical surface 19a and subsequently advances towards the second lens face 12 side.
Still further, as shown in FIG. 20, a filler material 22 composed of a light-transmissive adhesive material fills the space between the second recessing section 19 and the prism 20. The prism 20 is stably held within the second recessing section 19 by the adhesive force of the filler material 22. In addition, as shown in FIG. 20, the filler material 22 is also disposed on the shoulder section 21, and is used to bond the shoulder section 21 to the upper end surface 4a of the lens array main body 4. A thermosetting resin or an ultraviolet-curable resin can be used as the filler material 22 such as this.
In addition, the filler material 22 is formed having the same refractive index as the prism 20. For example, in some instances, the prism 20 is composed of Ultimo (registered trademark) manufactured by SUBIC Innovative Plastics Holding B.V. as a polyetherimide and the filler material 22 is composed of LumipluS (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc. In this instance, the refractive indexes of the prism 20 and the filler material 22 are both 1.64 in relation to light having a wavelength of 850 nm. In addition, for example, in some instances, the prism 20 is composed of ARTON (registered trademark) manufactured by JSR Corporation as a cyclic olefin resin, and the filler material 22 is composed of A1754B manufactured by TECS Co., Ltd. as an ultraviolet(UV)-curable resin. In this instance, the refractive indexes of the prism 20 and the filler material 22 are both 1.50 in relation to light having a wavelength of 850 nm.
Furthermore, as shown in FIG. 20, a reflective/transmissive layer 24 having a thin thickness is formed within the space formed by the second recessing section 19 and in a position on the upstream side in the advancing direction of the laser light La of each light-emitting element 7 in relation to the prism 20. Here, as shown in FIG. 20, the surface of the reflective/transmissive layer 24 on the first optical surface 19a side faces the first optical surface 19a with the filler material 22 therebetween, and the surface on the first prism face 20a side is in contact with the first prism face 20a. In some instances, the reflective/transmissive layer 24 such as this is formed by the first prism face 20a being coated with a single layer film composed of a single metal, such as Ni, Cr, or Al, or a dielectric multilayer film obtained by a plurality of dielectrics having differing dielectric constants (such as TiO2 and SiO2) being alternately stacked. In this instance, a known coating technique, such as Inconel deposition, is used for coating. When coating such as this is used, the reflective/transmissive layer 24 is formed into a very thin thickness of, for example, 1 μm or less. However, in some instances, the reflective/transmissive layer 24 is configured by a glass filter. In addition, the reflective/transmissive layer 24 is formed in parallel with the first prism face 20a. 
Here, as shown in FIG. 20, the laser light La of each light-emitting element 7 that has perpendicularly entered the first optical surface 19a advances straight towards the second lens face 12 side on the optical path within the filler material 22 filling the space between the first optical surface 19a and the reflective/transmissive layer 24 without refracting. At this time, when the filler material 22 is formed having the same refractive index as the lens array main body 4 as well, Fresnel reflection at the interface between the first optical surface 19a and the filler material 22 is suppressed. In this instance, the lens array main body 4 maybe composed of the same material as the prism 20. Furthermore, the laser light La of each light-emitting element 7 that has advanced into the filler material 22 between the first optical surface 19a and the reflective/transmissive layer 24 enters the reflective/transmissive layer 24. Then, the reflective/transmissive layer 24 reflects the incident laser light La of each light-emitting element 7 towards the third lens face 13 side at a predetermined reflection factor and transmits the laser light La towards the prism 20 side at a predetermined transmission factor. At this time, because the reflective/transmissive layer 24 has a thin thickness, the refraction of the laser light La transmitted through the reflective/transmissive layer 24 can be ignored (considered to be directly advancing transmission). As the reflection factor and the transmission factor of the reflective/transmissive layer 24, desired values are set based on the material, thickness, and the like of the reflective/transmissive layer 24, to the extent that an amount of monitor light M sufficient for monitoring the output of the laser light La can be obtained. For example, when the reflective/transmissive layer 24 is formed by the above-described single layer film, the reflection factor of the reflective/transmissive layer 24 can be 20% and the transmission factor can be 60% (absorption factor 20%), although depending on the thickness thereof. In addition, for example, when the reflective/transmissive layer 24 is formed by the above-described dielectric multilayer film, the reflection factor of the reflective/transmissive layer 24 can be 10% and the transmission factor can be 90%, although depending on the thickness and the number of layers thereof.
As shown in FIG. 20, during reflection or transmission such as this, the reflective/transmissive layer 24 reflects some (light amounting to the reflection factor) of the laser light La of each light-emitting element 7 that has entered the reflective/transmissive layer 24 as the monitor light M of each light-emitting element 7 corresponding to each light-emitting element 7, towards the third lens face 13 corresponding with each beam of monitor light M.
Furthermore, the monitor light M of each light-emitting element 7 reflected by the reflective/transmissive layer 24 in this way advances within the lens array main body 4 towards the third lens face 13 side, and is emitted from each third lens face 13 towards each light-receiving element 8 corresponding to each third lens face 13.
On the other hand, the laser light La of each light-emitting element 7 transmitted by the reflective/transmissive layer 24 enters the first prism face 20a immediately after transmittance. The direction of incidence of the laser light La of each light-emitting element 7 in relation to the first prism face 20a can be considered to be the same as the direction of incidence of the laser light La of each light-emitting element 7 in relation to the reflective/transmissive layer 24. This is because the reflective/transmissive layer 24 is very thin and the refraction of the laser light La by the layer 24 can be ignored. The laser light La of each light-emitting element 7 that has entered the first prism face 20a advances towards the second lens face 12 side on the optical path within the prism 20.
At this time, because the prism 20 is formed having the same refractive index as the filler material 22, when the laser light La of each light-emitting element 7 enters the first prism face 20a, refraction does not occur in the laser light La. The laser light La of each light-emitting element 7 that has advanced on the optical path within the prism 20 perpendicularly enters the second prism face 20b and is perpendicularly emitted outside of the prism 20 from the second prism face 20b. 
Next, the laser light La of each light-emitting element 7 emitted from the second prism face 20b perpendicularly enters the filler material 22 filling the space between the second prism face 20b and the second optical surface 19b. The perpendicularly incident laser light La of each light-emitting element 7 advances straight towards the second lens face 12 side on the optical path within the filler material 22 without refracting. At this time, because the filler material 22 is formed having the same refractive index as the prism 20, Fresnel reflection at the interface between the second prism face 20b and the filler material 22 is suppressed.
The laser light La of each light-emitting element 7 that has advanced within the filler material 22 between the second prism face 20b and the second optical surface 19b in this way is perpendicularly emitted from the filler material 22 and, immediately thereafter, perpendicularly enters the second optical surface 19b, as described above. The laser light La of each light-emitting element 7 that has perpendicularly entered the second optical surface 19b advances towards the second lens face 12 side on the optical path within the lens array main body 4 after the second optical surface 19b, and is then emitted by each second lens face 12 towards the end face of each optical fiber 3 corresponding with each second lens face 12.
As shown in FIG. 21, the second recessing section 19 is formed such that the bottom surface 19e as well as all side surfaces 19a to d of the second recessing section 19 fit within an area indicated by the outer shape of an opening section 19f of the second recessing section 19 when viewed from a surface-normal direction of the upper end surface 4a (above in FIG. 20). In other words, the second recessing section 19 is formed such that the respective projection surfaces in the surface-normal direction of the upper end surface 4a of the bottom surface 19e and all side surfaces 19a to d fit within the area indicated by the outer shape of the opening section 19f. The shape of the second recessing section 19 such as this is a shape enabling detachability from a mold to be ensured. This similarly applies to the above-described first recessing section 18.
In addition, as shown in FIG. 20 to FIG. 23, a pair of fiber-positioning projecting sections 25 are formed such as to be perpendicular to the left end surface 4c, on the left end surface 4c of the lens array main body 4 in positions on both outer sides of the lens formation surface 17a in the array direction of the second lens faces 12, as an optical-fiber positioning structure on the lens array side. The pair of fiber-positioning projecting sections 25 are formed into circular pin shapes (circular columnar shapes) having the same dimensions that project from the left end surface 4c towards the optical fiber 3 side.
On the other hand, as a configuration on the optical fiber 3 side corresponding with the pair of fiber-positioning projecting sections 25, as shown in FIG. 25, a pair of fiber-positioning recessing sections 26 are formed in the optical connector 10, as an optical-fiber positioning structure on the optical fiber side. However, in FIG. 25, because both fiber-positioning recessing sections 26 overlap in the direction perpendicular to the surface of the paper on which FIG. 25 is printed, only one fiber-positioning recessing section 26 towards the front of the paper surface is visible. The pair of fiber-positioning recessing sections 26 are formed into circular boss-hole shapes having the same dimensions such as to satisfy dimensional accuracy adhering to the standards (IEC61754-5, JISC5981) for F12-type multi-core fiber connectors.
As shown in FIG. 25, when the optical fibers 3 are attached to the lens array 1, the corresponding fiber positioning projecting sections 25 are inserted into the fiber positioning recessing sections 26. As a result, positioning of the optical fibers 3 when attaching the optical fibers 3 to the lens array 1 is performed.
Furthermore, as shown in FIG. 23, a pair of device-positioning recessing sections 28 are formed on the lower end surface 4b of the lens array main body 4 in positions on both outer sides of the lens formation surface 16a in the array direction of the first lens faces 11 and the third lens faces 13, as a photovoltaic-device positioning structure on the lens array side. The pair of device-positioning recessing sections 28 are formed into circular boss-hole shapes having the same dimensions, and the center axes thereof are formed in parallel with the optical axis OA(1) of the first lens faces 11.
On the other hand, as a configuration on the photovoltaic device 2 side corresponding with the pair of device-positioning recessing sections 28, as shown in FIG. 25, a pair of device-positioning projecting sections 29 are formed in the semiconductor substrate 5, as the photovoltaic-device positioning structure on the photovoltaic device side. However, in FIG. 25, because both device-positioning recessing sections 29 overlap in the direction perpendicular to the surface of the paper on which FIG. 25 is printed, only one device-positioning recessing section 29 towards the front of the paper surface is visible. The pair of device-positioning projecting sections 29 are formed into circular pin shapes having the same dimensions that extend in a direction parallel to the center axis of the outgoing light from the light-emitting elements 7.
As shown in FIG. 25, when the photovoltaic device 2 is attached to the lens array 1, each device-positioning projecting section 29 is inserted into the corresponding device-positioning recessing section 28. As a result, positioning of the photovoltaic device 2 when attaching the photovoltaic device 2 to the lens array 1 is performed.
(Bidirectional Communication-Supporting Lens Array)
Next, FIG. 26 is a vertical cross-sectional view of a bidirectional communication-supporting lens array 31, together with the photovoltaic device 2 and the optical fibers 3. In addition, FIG. 27 is a planar view of the lens array 31 shown in FIG. 26. FIG. 28 is a left-side view of the lens array 31 shown in FIG. 26. FIG. 29 is a bottom view of the lens array 31 shown in FIG. 26.
In the bidirectional communication-supporting lens array 31, the configurations and functions of the first lens faces 11, the second lens faces 12, and the first recessing section 18 are similar to those of above-described light monitoring-supporting lens array 1.
On the other hand, instead of each constituent section 20, 22, and 24 that obtains the above-described monitor light M, the bidirectional communication-supporting lens array 31 includes a configuration for supporting reception of optical signals.
In addition, a configuration supporting reception of optical signals is included on the photovoltaic device 2 side and the optical fiber 3 side as well.
In other words, as shown in FIG. 26, reception-dedicated second optical fibers 33 are arranged in parallel near the optical fibers 3 in the optical connector 10 (near the lower side in FIG. 26). The second optical fibers 33 are arrayed along the same direction as the array direction of the optical fibers 3 at the same pitch as the optical fibers 3. The number of second optical fibers 33 is also the same as the number of the optical fibers 3 (12 optical fibers). In addition, the number of second optical fibers 33 is the same as the number of light-receiving elements 8 and the number of third lens faces 13. Laser light LR is emitted from each end face 33a of the plurality of second optical fibers 33 facing the lens array 31, towards the lens array 31. The laser light LR is equivalent to optical signals for reception.
In addition, as shown in FIG. 26, fourth lens faces 14 are formed in positions adjacent to the second lens faces 12 in a direction perpendicular to the array direction of the second lens faces 12 (downward direction in FIG. 26) on the left end surface 4c of the lens array main body 4, in positions facing the end faces 33a of the second optical fibers 33, each fourth lens face 14 into which the laser light LR emitted from each second optical fiber 33 enters. The number of fourth lens faces 14 is the same as the number of second optical fibers 33. These plurality of fourth lens faces 14 are formed having a circular planar shape with the same dimensions as one another, and are formed in an array along the array direction of the second lens faces 12 at the same pitch as the second lens faces 12. In addition, an optical axis OA(4) of each fourth lens faces 14 is formed perpendicular to the left end surface 4c. The fourth lens faces 14 may have the same dimensions as the second lens faces 12.
Furthermore, as shown in FIG. 26, the second recessing section 19 has a second total reflection surface 34 that forms a portion in a predetermined area on the right end portion side on the bottom surface of the second recessing section 19. The second total reflection surface 34 is formed into a sloped surface such that the upper end portion thereof is positioned further to the left side in FIG. 26 than the lower end portion thereof. The second total reflection surface 34 maybe formed in parallel with the total reflection surface 18a of the first recessing section 18. The laser light LR of each second optical fiber 33 that has entered each fourth lens face 14 enters the second total reflection surface 34 such as this at an angle of incidence that the critical angle or greater from the left side in FIG. 26. The second total reflection surface 34 totally reflects the incident laser light LR of each second optical fiber 33 towards the third lens face 13 side (downward in FIG. 26).
The laser light LR of each second optical fiber 33 that has been totally reflected by the second total reflection surface 34 in this way is converged by each third lens face 13 and emitted towards the corresponding light-receiving elements 8. In other words, in the bidirectional communication-supporting lens array 31, the third lens faces 13 are used to collect reception optical signals instead collecting the monitor light M, and the light-receiving elements 8 are used to receive the reception optical signals instead of receiving the monitor light M.
On the other hand, in a manner similar to that in the light monitoring-supporting lens array 1, laser light LT of each light-emitting element 7 passes through the first lens faces 11, the total reflection surface 18a, the first optical surface 19a, and the second optical surface 19b in sequence, and is then emitted from each second lens face 12 towards the corresponding end face 3a of the optical fiber 3.
Ina configuration such as this, the laser light LR emitted from each second optical fiber 33 can be coupled with each light-receiving element 8 through the fourth lens faces 14, the second total reflection surface 34, and the third lens faces 13. Therefore, bidirectional communication can be effectively supported.
In the bidirectional communication-supporting lens array 31 such as this, for example, when a configuration separate from the lens array main body 4, such as a coating of reflective film (such as Au, Ag, or AL) on the total reflection surfaces 18a and 34, is not provided, the lens array 31 is the lens array main body 4 itself.
As conventional technology related to lens arrays such as this, proposals such as that in Patent Literature 1 has been made in the past    Patent Literature 1: Japanese Patent Application No. 2010-242124